1. Field of the Invention
This invention relates to an apparatus for loading a sheet-shaped material onto an inwardly concave curved surface. This invention particularly relates to an apparatus for loading a sheet-shaped material which carries out the loading by a simple mechanism.
2. Description of the Prior Art
Various sheet-shaped materials have heretofore been used for carrying out, for example, image read-out and recording in light beam scanning apparatuses such as light beam scanning read-out apparatuses and light beam scanning recording apparatuses. Also, as one of the sheet-shaped materials capable of recording image information thereon and subjected to the image read-out in the light beam scanning read-out apparatuses, there has heretofore been known a stimulable phosphor sheet as disclosed in, for example, U.S. Pat. Nos. 4,236,078, 4,239,968, 4,258,264, 4,276,473, 4,315,318 and 4,387,428 and Japanese Unexamined Pat. Publication No. 56(1981)-11395.
Specifically, when certain kinds of phosphors are exposed to a radiation such as X-rays, .alpha.-rays, .beta.-rays, .gamma.-rays, cathode rays or ultraviolet rays, they store a part of the energy of the radiation. Then, when the phosphor which has been exposed to the radiation is exposed to stimulating rays such as visible light, light is emitted by the phosphor in proportion to the stored energy of the radiation. A phosphor exhibiting such properties is referred to as a stimulable phosphor. The term "stimulable phosphor sheet" as used herein means a sheet-shaped recording material composed of the stimulable phosphor. In general, the stimulable phosphor sheet is composed of a substrate and a layer of the stimulable phosphor overlaid on the substrate. The stimulable phosphor layer comprises a binder and the stimulable phosphor dispersed therein. In the case where the stimulable phosphor layer is self-supporting, the stimulable phosphor layer itself can constitute the stimulable phosphor sheet.
On the other hand, in the aforesaid light beam scanning apparatuses and the like, it is often necessary to hold the sheet-shaped material along an inwardly concave curved surface such as a cylindrical surface for various purposes. For example, a light beam scanning apparatus is disclosed in Japanese Unexamined Pat. Publication No. 62(1987)-92572 wherein a light beam scanning system is accommodated in a cylindrical optical unit, a semi-cylindrical holding means surrounds the optical unit, and a scanning sheet which is to be scanned is fed by feed rollers from one end of the holding means along the inner surface of the holding means and disposed on the holding means. In the disclosed light beam scanning apparatus, the optical unit provided with a light deflector for scanning in the main scanning direction deflects scanning light in the main scanning direction and, at the same time, is rotated in the sub-scanning direction with respect to the scanning sheet secured to the holding means, thereby to carry out two-dimensional scanning. With this technique, the apparatus as a whole can be made smaller than in the case where the scanning in the sub-scanning direction is carried out by conveying the scanning sheet.
In the apparatus for scanning by securing the sheet-shaped material to the holding means, it is necessary for the sheet-shaped material to be secured reliably along the inwardly concave curved surface of the holding means. However, in the case where the sheet-shaped material is the stimulable phosphor sheet by way of example, the stimulable phosphor sheet is comparatively rigid and therefore often separates from the curved surface. Thus a need exists for an apparatus for loading a sheet-shaped material such that a comparatively rigid sheet-shaped material such as the stimulable phosphor sheet is loaded onto a curved surface such as a cylindrical surface reliably without separation from the curved surface.